Robert J. Runser

Experimental demonstration and scalability analysis of a four-node 102-Gchip/s fast frequency-hopping time-spreading optical CDMA network

We present experimental and simulation results from a 102-Gchips/s incoherent wavelength-hopping time-spreading optical code-division multiple-access testbed, utilizing four 50-GHz ITU grid wavelengths. Error-free operation of four users is obtained with an effective power penalty /spl sim/0.5 dB. Simulation studies show scalability to >10 users with an effective power penalty of /spl sim/4 dB. The simulation study of the impact of asynchronous access on the performance allows for a complete network design from an engineering viewpoint.

Experimental investigation of quantum key distribution through transparent optical switch elements

Quantum key distribution (QKD) enables unconditional physical layer security for the distribution of cryptographic key material. However, most experimental demonstrations have relied on simple point-to-point optical links. In this paper we investigate the compatibility of QKD with reconfigurable optical networks. By performing the first tests of QKD transmission through optical switches, we study if there are impairment mechanisms other than switch insertion loss that impact the sifted and error corrected secret bit yield. Three types of transparent optical switch elements are investigated including lithium niobate (LiNbO/sub 3/), microelectromechanical systems (MEMS), and optomechanical. We show that QKD can be extended beyond point-to-point links to switched multinode architectures including protected ring networks to enhance quantum channel availability.

Single-shot optical sampling oscilloscope for ultrafast optical waveforms

We present an all-optical technique for measuring single-shot optical pulse phenomena using a feed-forward pulse replicator and a compact, nonlinear loop mirror called the terahertz optical asymmetric demultiplexer (TOAD). By exploiting the fast nonlinearity of a semiconductor optical amplifier (SOA) placed asymmetrically within the loop, a sampling window on the order of a few picoseconds can be used to detect features in low-energy (<pJ) optical waveforms. We successfully demonstrate a sampling system with 10-ps resolution capable of sampling single-shot optical waveforms up to 160 ps in duration. The sampled real-time pulsewidth agrees well with standard, long-range space autocorrelation.

Routing of 100 Gb/s words in a packet-switched optical networking demonstration (POND) node

This paper presents the design and experimental results of an optical packet-switching testbed capable of performing message routing with single wavelength time division multiplexed (TDM) packet bit rates as high as 100 Gb/s. The physical topology of the packet-switched optical networking demonstration (POND) node is based on an eight-node ShuffleNet architecture. The key enabling technologies required to implement the node such as ultrafast packet generation, high-speed packet demultiplexing, and efficient packet routing schemes are described in detail. The routing approach taken is a hybrid implementation in which the packet data is maintained purely in the optical domain from source to destination whereas control information is read from the packet header at each node and converted to the electrical domain for an efficient means of implementing routing control. The technologies developed for the interconnection network presented in this paper can be applied to larger metropolitan and wide area networks as well.

Comparison of three nonlinear interferometric optical switch geometries

We present an experimental study of ultrafast all-optical interferometric switching devices based upon a resonant nonlinearity in a semiconductor optical amplifier (SOA). We experimentally compare three configurations: one based upon a Sagnac interferometer and the other two based upon Mach-Zehnder interferometers. By using picosecond pulses, we characterize the switching window of the three devices in terms of both temporal width and output peak-to-peak amplitude. These results are found to be in close agreement with a previously developed theoretical model. Since these nonlinear interferometric switches use an active device as the nonlinear element, relatively low control pulse energy is needed to perform switching as compared to other techniques. As a result, these optical switches are practical for all-optical demultiplexing and ultrafast optical sampling for future lightwave communication systems.

Interferometric ultrafast SOA-based optical switches: From devices to applications

All-optical switches are fundamental building blocks for future, high-speed optical networks that utilize optical time division multiplexing (OTDM) techniques to achieve single channel data rates exceeding 100 Gb/s. Interferometric optical switches using semiconductor optical amplifier (SOA) non-linearities perform efficient optical switching with < 500 fJ of control energy and are approaching optical sampling bandwidths of nearly 1 THz. In this paper, we review work underway at Princeton University to characterize and demonstrate these optical switches as processing elements in practical networks and systems. Three interferometric optical switch geometries are presented and characterized. We discuss limitations on the minimum temporal width of the switching window and prospects for integrating the devices. Using these optical switches as demultiplexers, we demonstrate two 100-Gb/s testbeds for photonic packet switching. In addition to the optical networking applications, we have explored simultaneous wavelength conversion and pulse width management. We have also designed high bandwidth sampling systems using SOA-based optical switches as analog optical sampling gates capable of analyzing optical waveforms with bandwidths exceeding 100 GHz. We believe these devices represent a versatile approach to all-optical processing as a variety of applications can be performed without significantly changing the device architecture.

Demonstration of 1550 nm QKD with ROADM-based DWDM Networking and the Impact of Fiber FWM

We demonstrate compatibility of 1550 nm QKD with a MEMS-based ROADM and also show that four-wave mixing resulting from copropagating DWDM signals can become the dominant source of background noise within the QKD channel passband.

All-optical OCDMA code-drop unit for transparent ring networks

In this letter, we propose and experimentally demonstrate a novel all-optical two-dimensional time-wavelength optical code-division multiple access (OCDMA) code-drop unit for transparent ring networks. The ultrafast all-optical code-drop unit is based on the terahertz optical asymmetric demultiplexer. We have demonstrated experimentally the capability to drop the correlated code at the desired node in a four-user ring network operating at 253 Gchips/s with a single-user bit rate of 2.5 Gb/s. Error-free operation is obtained. Dropping codes from multihop networks facilitates the development of optical add-drop multiplexers for OCDMA networks.

A highly-scalable, rapidly-reconfigurable, multicasting-capable, 100-Gb/s photonic switched interconnect based upon OTDM technology

We describe an ultrafast photonic switched interconnect based upon technologies developed for optical time division multiplexing (OTDM). The system uses a time-interleaved broadcast-and-select star architecture that is functionally equivalent to a crossbar switch. The interconnect offers full connectivity and low uniform latency among the input and output ports. The enabling technologies include ultrafast gated time slot tuners and all-optical demultiplexers. By utilizing these advanced optical technologies, it is possible to construct a highly scalable, rapidly reconfigurable, ultra-high-speed switch with performance beyond the capacity of current electronics. In the experimental demonstration, we constructed an interconnect with a peak bit rate of 100 Gh/s and the capability of connecting 16 OTDM ports. The system successfully demonstrated error-free operation of 100 Gb/s-multiplexing and demultiplexing in addition to rapid inter-channel switching capability on the order of the single channel bit period. The system also supports multicasting functions among many nodes. To scale the system to accommodate a large number of ports, we provide an analysis of the coherent crosstalk requirements through the network to show the potential to support hundreds of ports within practical constraints of the optical components. We believe that this system offers an approach to meet the demands of high bandwidth and fast switching capability required in current high-speed lightwave networks.

Experimental characterization of the separation between wavelength-multiplexed quantum and classical communication channels

Quantum key distribution (QKD) is a new technique for secure key distribution based on the laws of physics rather than mathematical or algorithmic computational complexity used by current systems. Understanding the compatibility of QKD at 1310 nm with the existing commercial optical networks bearing classical wavelength-division-multiplexed (WDM) channels at 1550 nm is important to advance the deployment of QKD systems in such networks. The minimum wavelength separation for multiplexing QKD and WDM channels on a shared fiber is experimentally determined for impairment-free QKD+WDM transmission.